Glass prism-plate.



Patnted Aug..7, I900. a. FUGMAN.

GLASS PRISM PLATE.

(Application filed May 31 1900.

(No Model.)

lNVENTOR NITED STATES PATENT. OFFICE.

GODFREY FUGMAN, OF CLEVELAND, OHIO.

GLASS PRISM-PLATE.

SPECIFICATION forming part of Letters Patent No. 655,220, dated August7', 1900. Application filed May 8, I900. serial No. 15,313. (No model.)

T0 at whom it may concern:

Be it known that I, GODFREY FUGMAN, a resident of Cleveland, in thecounty of Guyahoga and State of Ohio, have invented certain new andusefullmprovements in Glass Prism- Plates; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it pertains tomake and use the same.

My invention relates to improvements in glass prism-plates.

The object of this invention is more especially to improve upon theconstruction of prism-plate disclosed in United States Letters PatentNo. 627,848, granted to me June 27, 1899, and to produce a prism-platethat has a vast refracting capacity and great brilliancy, that isexceedingly strong, and requires less material in its construction.

With this object in view the invention consists in certain peculiaritiesof construction hereinafter described, and. pointed out in the claims.

In the accompanying drawings, Figure I is an inner side view of myimproved prismplate. Fig. II is a view in perspective of a portion ofthe plate. Fig. III is a section on any one of lines III III, Fig. I.

My improved prism-plate comprises a glass plate whose body portion ispreferably plain and smooth on its outer and light-receiving side a andhas its inner and light-refracting side provided with numerous inwardlyand laterally projecting prismatic lugs 19. Some of the lugs that arelocated next adjacent the edges of the plate are not perfect or completelugs; but each complete lug b has preferably a diamond-shaped orlozenge-shaped refracting-surface c, facing inwardly and arrangedobliquely to the plane of the body portion of the plate. Preferably eachcomplete lug b has its refractin'g-surface 0 arranged with two oppositecorners thereof in line horizontally and with the two remaining cornersforming the upper extremity and lower extremity, respectively, of thesaid surface, and the lug is widest at its central portion centrallybetween its upper and lower extremities. Each complete lug b of theplate illustrated is thinnest at its lower angular extremity and isgradually increased in thickness from the said extremity toward itsupper extremity, and the top edges of the lug form two refractingshoulders or surfaces 0 and c, that diverge from the upper extremity ofthe lug toward the lugs central portion and slope also in the directionof the diamond-shaped or main refracting-surface c of the lug, and hencethe said lug in the case illustrated has three refracting-surfaces--amain refracting-surface c,facin'g inwardly and somewhat downwardly, andtwo other and narrower refracting-surfaces 6 and e, that form the topedges of the lug and diverge downwardly from the upper extremity of thelug and slope somewhat toward the lugs main retracting-surface.Preferabl y the lugs 17 are arranged in horizontal rows, with the lugsof each row of lugs alternating with the lugs of the adjacent row orrows of lugs, with each side corner of each lug of each row of lugscoincident orapproximately coincident with the adjacent side corner ofthe adjacent lug of the said row of lugs, with the upper corner of eachlug of each row of lugs coincident or approximately coincident withadjacent side corners of two adjacent lugs of the next upper row oflugs, and with the lower corner of each lug coincident or approximatelycoincident with the adjacent side corners of two adjacent lugs of thenext lower row of lugs. It will be observed also that the adjacentrefractiug edges 6 of adjacent lugs of each row of lugs convergedownwardly and meet at the inner extremity of the junction of theupwardly-converging sloping edges 6 of a lug of the next lower row oflugs, so that a V-shaped recess is formed between adjacentdownwardly-converging sloping edges e of adjacent lugs of each row oflugs and that the main refracting-surface c of a lug of the next upperor adjacent row of lugs overhangs the said recess.

By the construction of prism-plate hereinbefore described theobjectionable casting of shadows by the lugs is avoided,a large refracting capacity is obtained, the plate possesses great brilliancy, isexceedingly strong and durable, and can be manufactured with facilityand with comparatively-little material.

What I claim is l. Aprism-plate of the character indicated, having itsinner side provided with a plurality of prismatic lugs that have each amain ICO sloping refracting-surface that faces inwardly and is arrangedobliquely to the plane of the body portion of the plate, which surfaceis widest at its central portion and gradually reduced in width towardits upper and lower extremities.

2. A prism-plate of the eharacterindicated, having its inner sideprovided with a plurality of lugs that have each a main sloping surfacethat faces inwardly and is arranged obliquely to the plane of the bodyportion of the plate, which surface is widest at its central portion andreduced in width toward its thicker and thinner extremities, and twoshoulders or edges formed upon opposite sides, respectively, of thethicker portion of the lug.

3. A prism-plate of the character indicated having its inner sideprovided with a plurality of prismatic lugs that have each a mainsloping surface that faces inwardly and is arranged obliquely to theplane of the body portion of the plate, which surface is widest at itscentral portion and gradually reduced in width toward its upper andlower extremities, and two shoulders or edges formed upon oppositesides, respectively, of the thicker portion of the lug and extending anddiverging from the thicker extremity of the lug toward the centralportion of the lug.

4. A prism-plate of the character indicated, having its inner sideprovided with a plurality of prismatic lugs having each a diamond-shapedor lozenge-shaped refractingsurface facing inwardly and arrangedobliquely to the plane of the bodyportion of the plate and arranged withtwo corners thereof forming opposite side extremities, respectively, ofthe surface and with the remaining two corners thereof forming the upperextremity and lower extremity, respectively, of the said surface.

5. A prism-plate of the character indicated, having its inner sideprovided with rows of prismatic lugs that are each provided withinwardly-facingrefraeting-surfaces arranged obliquely to the plane ofthe body portion of the plate and widest at the central portion.

6. Aprism-plate of the character indicated, having its inner sideprovided with rows of prismatic lugs having lozenge-shaped ordiamond-shaped refracting-surfaces c facing inwardly and arrangedobliquely to the plane of the body portion of the plate.

Signed by me at Cleveland, Ohio, this 28th day of April, 1900;

GODFREY FUGMAN.

Witnesses:

G. H. DORER, A. H. PARRATT.

